• question_answer Two carnots engines A and B are operated in series. The first one A receives heat at 1200 K and rejects to a reservoir at T and K. The second engine B receives the heat rejected by the first engine and in turn rejects to a heat reservoir at 300 K. Calculate the value of T, when work outputs of the two engines are equal. A) 600 K B) 750 K C) 450 K D) 900 K

 [b]$\frac{W}{{{Q}_{1}}+W}={{\eta }_{1}}$ $\frac{W}{{{Q}_{1}}}={{\eta }_{2}}$ $\frac{W}{{{Q}_{1}}}=1-\frac{300}{T}$ $\Rightarrow$ $\frac{1}{1+\frac{T}{T-300}}=\frac{1200-T}{1200}$ $\Rightarrow$$(T-300)1200=(1200-T)(2T-300)$ $T=750K$